1. Technical Field
The present invention relates to coupling the output of a laser diode or gas laser to an optical fiber.
2. Background Art
Light emitted from a laser diode is highly divergent and elliptical. Accordingly coupling optics, such as a spherical lens, graded index lens, or a collimating/focusing lens set, is commonly used to match the emitted light to a light-receiving device. When the light-receiving device is an optical fiber, and particularly a single-mode optical fiber, the coupling becomes very sensitive to positional misalignments between the incoming light beam, the focusing lens, and the end of the optical fiber.
U.S. Pat. No. 5,351,330 discloses an optical alignment structure for a laser diode lens and an optical fiber. The structure includes a lens holder with a plurality of adjustment screws for changing the transverse position and angular orientation of coupling optics in the optic axis to steer the beam. The disclosure also provides for adjusting the longitudinal position of the end of the optical fiber along the optic axis by loosening a threaded set screw, sliding the optical fiber to a desired position, and re-tightening the set screw. Such a system for adjusting the longitudinal position of the end of an optical fiber is not sufficiently accurate for many applications. Further, the mere act of tightening the set screw may tend to distort and de-focus the end of the optical fiber.